GB411638A - Improvements in or relating to modulated carrier wave transmitters - Google Patents

Abstract

411,638. Valve modulating circuits. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Marconi House, Strand, London.- (Assignees of Ussehnan, G. L. ; Port Jefferson, New York, U.S.A.) April 3, 1933, No. 9999. Convention date, April 1, 1932. [Class 40 (v).] Relates to phase modulation and comprises a system in which the modulating valves have their input and output electrodes in push-pull relation. The carrier frequency generated by a source A supplies a tank circuit H connected in push-pull to the grids of valves 7, 10 through phase retarding and advancing means I and J respectively. The grids of valves 7, 10 are also supplied with modulating potentials from a source B and push-pull transformer T through resistances R1, R2 respectively the low high-frequency potential ends of which are connected to the cathodes through condensers M, N respectively. The grid-anode capacities of valves 7, 10 are neutralized by condensers K, L, connected between anode of valve 10 and grid of valve 7 and anode of valve 7 and grid of valve 10 respectively, the anodes being connected in push-pull to a tank circuit 22 feeding an amplitude limiter D, amplifier and /or frequency multiplier F and aerial system. In a modification (Fig. 2 not shown) screen-grid modulating valves are used, the modulating potentials being amplified and applied to the screening grids. Specification 357,479 is referred to.